Biofilm formation of the thermophilic Anoxybacillus rupiensis strain DSM 17127 on abiotic surfaces and removal of its biofilm structure on polystyrene surfaces

The aim of this study was to examine the biofilm formation of Anoxybacillus rupiensis DSM 17127 on abiotic surfaces used in the industry and to remove the biofilm structure formed on polystyrene surfaces with sanitation agents. The genomic DNA (gDNA) and the extracellular DNA (eDNA) in the biofilm matrix structure of the bacteria were determined by spectrophotometric analysis and agarose gel imaging. For the biofilm formation on abiotic surfaces and the removal of the biofilm structure formed on polystyrene surfaces, crystal violet binding assay was applied. The optimum temperature, pH, and salinity for the growth and biofilm formation of the bacteria were 55 C, 8.0, 1 % and, 60 C, 8.0, 0 %, respectively. The molecular weight of gDNA (27.6 kb) was determined to be larger than eDNA (20.9 kb). gDNA and eDNA were partially purified and treated with DNase I, RNase A and proteinase K. The purified gDNA was completely disrupted only by DNase I., and the purified eDNA was resistant to all three enzymes. As a result of the treatment of biofilm containing eDNA with DNase I, it was observed that the eDNA was sensitive to DNase I and the biofilm mass decreased by 80 % within 2 hours. The bacterium was observed to form biofilms on polycarbonate, polypropylene, polyvinyl chloride, stainless steel, polystyrene and glass surfaces, and the most ideal surface determined as polycarbonate (5.69 log cfu/cm). In the biofilm removal studies, protein degrading sanitation agents were found to be more effective than polysaccharide degrading agents. In conclusion, it was determined that the eDNA of the bacteria plays an important structural role in the integrity and robustness of the mature biofilm matrix. In addition, it was showed that the bacterium is capable of forming biofilms on abiotic surfaces. Dairy industrial sanitation agents had a significant effect on the removal of the biofilm mass of Anoxybacillus rupiensis.